Spanning Tree protocol history

Den originale Spanning Tree Protocol IEEE 802.1D var udviklet til Bridgede eller Switchede netværk uden VLAN's. Derfor var det nødvendigt at videreudvikle Spanning tree protokollen for at tilgodese netværk der anvender VLAN.

Cisco anbefaler at man anvender PVST+ i større netværk, men mange andre anbefaler anvendelsen af MST da det er en IEEE standard, samt at konfigurationen er mere overskuelig.

Spanning tree protokoller

Protokol	Standard/Proprietær	Årstal	Instanser	Trunk typer	Rapid	Virker sammen med
STP	IEEE 802.1D-1990	1990	1	ingen	Nej	-
CST	IEEE 802.1Q-1998	1998	1	IEEE 802.1Q	Kan anvendes	-
MST	IEEE 802.1Q-2005	2005	(Cisco 16)	IEEE 802.1Q	Kan anvendes	-
PVST	Cisco proprietær	-	Per-VLAN	ISL	Kan anvendes	-
PVST+	Cisco proprietær	-	Per-VLAN	IEEE 802.1Q,ISL	Kan anvendes	PVST,PVST+,CST

Bemærk: Rapid Spanning Tree Protocol (RSTP) er implementeret i RPVST+. Når Cisco dokumentation ofte næver RSTP betyder det at der anvendes RPVST+.

Cisco og Spanning-Tree

Default Spanning-Tree protokol på Cisco Switche er PVST+ (Per-VLAN Spanning Tree plus) som er vist som pvst.

Cisco PVST+

Dist2#<input>conf t</input>
Enter configuration commands, one per line.  End with CNTL/Z.
Dist2(config)#<input>spanning-tree mode ?</input>
  mst         Multiple spanning tree mode
  <notice>pvst        Per-Vlan spanning tree mode</notice>
  rapid-pvst  Per-Vlan rapid spanning tree mode

Dist2(config)#<input>spanning-tree mode pvst</input>
Dist2(config)#<input>^Z</input>
*Mar  1 00:16:47.111: %SYS-5-CONFIG_I: Configured from console by console
Dist2#<input>show spanning-tree summary</input>
Switch is in <notice>pvst mode</notice>
Root bridge for: none
Extended system ID           is enabled
Portfast Default             is disabled
PortFast BPDU Guard Default  is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default            is disabled
EtherChannel misconfig guard is enabled
UplinkFast                   is disabled
BackboneFast                 is disabled
Configured Pathcost method used is short

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001                     0         0        0          3          3
VLAN0100                     0         0        0          3          3
---------------------- -------- --------- -------- ---------- ----------
2 vlans                      0         0        0          6          6

Cisco RPVST+

Dist2#<input>conf t</input>
Enter configuration commands, one per line.  End with CNTL/Z.
Dist2(config)#<input>spanning-tree mode rapid-pvst</input>
Dist2(config)#<input>^Z</input>
*Mar  1 00:16:47.111: %SYS-5-CONFIG_I: Configured from console by console
Dist2#<input>show spanning-tree summary</input>
Switch is in <notice>rapid-pvst mode</notice>
Root bridge for: none
Extended system ID           is enabled
Portfast Default             is disabled
PortFast BPDU Guard Default  is disabled
Portfast BPDU Filter Default is disabled
Loopguard Default            is disabled
EtherChannel misconfig guard is enabled
UplinkFast                   is disabled
BackboneFast                 is disabled
Configured Pathcost method used is short

Name                   Blocking Listening Learning Forwarding STP Active
---------------------- -------- --------- -------- ---------- ----------
VLAN0001                     0         0        0          3          3
VLAN0100                     0         0        0          3          3
---------------------- -------- --------- -------- ---------- ----------
2 vlans                      0         0        0          6          6